Paper making process utilizing modified locust bean gum



Patented July 7 1953 OFFICE rm ER MAKING PROCESS U'rmzmo MODI- FIED LOCUSVT BEAN GUM' Nat Frisch, White Plains, andl rank J. Sweeney,

ForestHills, N. Y., assignors to Stein, Hall, &' Company, Inc., New York, N. Y a corporation of New York No Drawing. Application December16, 19,48,

. Serial No. 65;717 I 3Glaims. 1 The present invention relates to an improvement in the process of mal ging paper and to improved paper produced thereby. V

Many attempts'have been made in thepast to speedup the paper makingfprocess and to increase 'thestrength of the paper formed thereby. Thus, for example, it has been proposed to incorporate into the paper stock ,locust' bean gum or flour preparedfrom the seed'endosperm of the locust or carob' tree (Cemtoma enigma a perennial legume native to the Mediterranean region. The fruit of this tree isin the form of pods. It was known to the ancients asmanna and in'la'ter periods has been known as St. Johns bread. The gum powder generally known as'* locust bean gum is obtained from the-seeds in these pods and has been utilized heretofore as a film forming material in textile sizing and as a thickening agent in printing and dyeing.

It is-known that the addition of locust bean gum to paper stool; will result in paper having improved wetand dry strength characteristics. The use of locust gean gum in the manufacture of paper hasjhowever, been discouraged due to the considerable difliculty involvedin'un'ifor'mly distributing the locust bean gum throughout the aqueous furnish. Even when specialequipment in the form of injectors and high speed stirrers is used and the locust'bean gum is added slowly to water, an appreciable proportion of the locust .bean gum will remain in the form oflumps even after cooking. If these lumps get into the sheet" they cause fisheyes and later cause a break down in the sheet. Special equipment must therefore b utilized to strain out. these lumps, which incidentally result in a waste of locust bean gum, and the tanks in which the gum is mixed and cooked must frequently'be drained and cleaned. The additional equipment required and the precautions that must be followed in order to incorporate locust bean gum in paper stock have substantially offset the advantages obtained by use ofthe gum with the result that the use of locust bean guminthepaper industry ha not become widespread. Y j

It has now been found that conventional paper making operations can lie-materially improved by adding to .theaqueous. suspension of fibers, normally referred to as the furnish, at a pointafter all operations designed to substantially modify '2- thefibrous' constituents by mechanical means are completed and prior tothe formation of the web, i. e., preferably at the-head box, fan pump or stock regulator box, an aqueous solution of a combination of, locust bean'gum, an alkali metal borate and an aldehyde selected from'the group consistingof'glyo'xal and pyruvic aldehyde prepared preferably by th'e'cooking operations subsequently disclosed.

This method avoids the difficulties involved-in adding straight locust'bean gum tothe furnish, significantlyimproves the" Serial-Nb; 65,718, filedDecember 16, l94'8','with' utmostfacility-in any oneoi a;- number of ways.

A' dry mixtureoi." locust bean gum, borate and aldehyde may be "dispersed readily in cold water Ora dry'mixture of'locust beangum and borate may first be dispersed in cold water and the aldehyde added to the aqueous dispersion so for-med. Neither of these methods results in the formation of objectionable lumps and the complete dispersion of the materials can be accomplished in a matter of seconds. The dispersion isthen cooked at arr-elevated-temperature of the order of abo'ut F.:to 2 12 F., preferably about 200 F. to open, swell or gelatinize the locust bean gum andth'erebyforni' a clear and viscousaqueoussolution'.

Fests haveshown'that' in a sheet into which this material has been incorporated, an improvement in formation results, and also that the'ad dition of the material of this invention results in a generalimprovement in the quality of paper' produced from a given stock. Theutilization' of this invention, for example, has'made it possible to increasethe-capacity of a mill having limited dryingfacilities' without reduction in salient properties by'making it possible to use" stock ofincreased freeness' thereby permitting a greateramount of water to; drain fromthe web during passage over the-wirepriorto drying. Also the capacity: ofa millto produce a uniformly good quality paper hasbeenin'creased in view of the improved-web formation from mediocreor poor stock. Thus, for example, it has been found that that lower drying temperatures or increased.

4 ticable because that would involve increasing the capacity of the cooking vessel or supply tank and of the pumping equipment utilized to add the cooked solution to the furnish. It is preferable therefore to maintain the pH between about 3 and 10 so that the cooked solution will not be too viscous and at the same time not too acid to pre-. vent or inhibit gelatinization of the locust bean gum. While it is possible to carry out the process of this invention at either extreme pH value, it'has beenv found @that optimum results are ob- I tained by maintaining the pH at about 8.0 to 8.2.

. Within this more limited range, the locust bean speeds are possible with attendant savings while attaining the same or greater amount of pro-; duction and the same or improved quality of final product.

gum will become gelatinized quite readily and the viscosity of the cooked solution is sufiiciently flow to permit easy transference of the cooked gredients used in the combinationthave con- Q siderable effect upon the results obtained in so far as handling and dispersibility are concerned. As the proportion of locust bean gum in the combination is decreased, the ease with which it can be dispersed in water is increased. On the other hand, as the proportion of locust bean gum in the combination approaches 100%, itbecomesmore difficult to disperse in water .and more liable to form-lumps that must be strained out prior to the addition of the solution to the furnish. As a practical matter, the presence of less than about 50% locust bean gum in the combination is too little to obtain thefull benefits derived from its use and the presence of more than about 96% of I, the gum will result in sufiicientdispersingdifrlculties to make its use uneconomical. It is generally preferred therefore to limit the proportion of locustbean gum in-the combination to between about 65% and 93%. Optimum .results have been obtained with concentrations of between 85% and 90%.

Changes in the relative proportions of borate and aldehyde also have a considerable efiect upon the results obtained in the paper making ;operation and more particularly upon the consistency and characteristics in i the aqueous. solution formed when the-combination'is added to water and cooked. The borate tends to impart to thecooked solution a heavy'body, high film strength and stringiness. The aldehyde reduces the ropiness of the cooked solution, imparts a long stringy character thereto-and reduces its viscosityto a level thatmakes handling of the solution practicable. J

It has generally been found desirable to adjust the relative proportions of locust bean; gum;

borate and aldehyde so' that the dispersion thereof in water=before cooking or,the--solution thereof after cooking will havei-a'pl-Lbetween about 3 and 10. The lower limit of the pI-I'range is determined by the characteristics of the particular locust .bean gum in the combination and particularly by its ability to open or become gelatinized when cooked. If the pH is reduced to a value below about 3, it becomes extremely difiicult, and in some cases impossible, to gelatine ize the locust bean gum by cooking. The upper limit of the pH range is determined by the viscosity of the cooked solution. It is essential in practice that the cooked solution be not so. viscous that it cannot readily be transferred from regulator box; Reduction of the viscosity simplyby diluting the solution with water is 10 P solution from a supply source to the head box,- stock regulator'box, fan pump, or to any other point atwhichthe combination is added to the furnish. ,Satisfactory viscosity and gelatinization conditions are normally obtained by main-- taining the ratio of borate to aldehyde at between about 1:1 and 3:1 and preferably at about 2:1.

.=-A mixture that has been found to be particularly successful is one containing 85% by weight of locust bean gum, 10%' by Weight of borate and 5% by weight of aldehyde. When. a handful of. this mixture is simply dumped into cold water, it at first floats onthe surface.- Within .afew seconds, however, the mass of material-breaks up into smaller portions which fall to the bottom until all of it has left the surface ofthe water. Simple stirring of the Water will thereupon form a uniform'dispersion of the material which, upon being cooked to a temperature of about 200 F., will form v a viscous, stringy and transparent solution. I ,1

By way of contrast, when straight locust bean gum is dumped int'o cold water, only a small portion of it-may fall to the bottom and most of the locust bean gum remains floating on the surface. The outerportions of the' mass apparently absorb/water, swell and become sticky so as to form a coating that denies access of water to the interior of the mass. Vigorous stirring fails to produce -.a uniform distribution of the gum 7 throughout the water and cooking thereof at 200 F. results in a syrupy mass containing lumps which must be removed before it can be added to thefurnish.

When it is desired to employ mixtures having concentrations of locust bean gum that are less than about starch may be added to make gum, 17% starch, 10% borate and 5% aldehyde.

Small amounts of oxidizing agents, such as barium peroxideand sodium perborate may be added to thin out the solution prepared when a the combination is dissolved in water.

The borate may be any suitable borate such as, for example, sodium tetraborate (borax) and sodium metaborate.

The aldehyde may be glyoxal or 'pyruvic aldehyde, or a combination of said materials. The presence of glyoxal in the combination is particularly desirable becauseit promotes anextremely rapid and facile dispersion of the mixture in cold water. I Amixture' consisting of locust bean'gum, 10% borax and 5% glyoxal, for example, will readily and completely disperse in water at room temperature in as little as '1 SfiQOHdS'.

dilute state, e. g.,.O.5%-.

' Citric Acid 1% solution of the mixture ismade by adding it, in the form of a dry powder, to one half the required amount of water whilethe water is cold,

then cooking to 200 F. and finally adding the remaining water required to produce a 1% solution. This solution is then added to the pulp inthe head box, at the fan pump or in the regulator box at a rate sufficient to add from about 1 to 20 or 30 lbs. of the mixture, based on the dry weight thereof, to a ton of furnish, likewise based on the dry weight thereof. As in ordinary paper making processes, the concentrated stock, consisting of a maximum of approximately 4% solids, is dilutedv at the fan pump to a muchmore .The addition of .a solution of locust bean gum, borate and. aldehyde to, a paper stock permits increasing the freeness .of the stock,- reducing the power consumption inthe refining phases and the steam consumption in the dryer section, all of which makes possible an increase in the speed at which the'paper is run ed, and generally improves the characteristics of the paper produced at a given set of machine conditions.

A number of typical formulae are'listed in Tables 1 and 2 below, the numerals therein r'eferring to percentages by weight.

Table 1 6 ft. per-minute, the machinardrew afififl. lbs: per hour and the pH of the stock suspension was 5.1. The furnish" consisted of. spruce and. soda'pulp. For a perio'dof about ithree hours'rduringthe run the mixture in the mixing tank 'wasadded at a rate equivalent to 5lbs. of solid mixture :per

ton of paper. based flnithe dlfy weight; or: 0.25%

of the dry weight of the-furnish. Fortwoadditional hours the rate of flow from the mixingtank was doubledito 7.5 gallons per minute.

Ledger 1'un. 42v lbs. of amixture' of'locust bean gum, boraxand-glyoxal in proportions of 10% and 5%, respectively,"were mixed, cooked and diluted with water:under the same conditions as described in the bond run.

White ledger paper was run ofi on a Fourdriniermachirle with the addition of 5% starch at the fan pump. The roll width was 102", the

machine drew 3410 lbs. per hour and .the'iJI-I of the stock suspension was 520. The solids in the furnish consisted of spruce and ,soda'pulp. The web was passed through" a starch siz'e tub throughout the run.

For a period of about three hours during the run the addition of 5% starch at the fan pump was cut oil and the mixture in the mixingtank was addedat the fan pump at a rate, of 0.5% by weight of dry mixture based on the dry weight of the furnish. Thereafter the addition 015% starch was resumed atthe fan pump.

The results'of these runs indicated that thein Formula No 2 Locust Bean Gum Borax Glyoxal Pyruvic Aldehyde Ammonium Chloride Table 2 FormlflaNo 12 I 13 14 I 15 I 16' Locust Bean Gum; Powdered Potato Starch Glyoxal Bol'ic Acid Aluminum Sulfate Barium Peroxide Sodium Perborat Dowicide A Dowicide A is a Well known preservative known generically as sodium orthophenylphenate.

In order to further illustrate the inventionv without, however, intending to limit its scope thereto, the following examples are included;

EXAMPLE 1 .Bond rum-In a paper mill 500' gallons of water and 42'lbs. of a, mixture consisting ofv 85% locust bean sum, 10% borax and 5 glyoxal were introduced into a mixing tank having a diameter of 5%; ft., a, height of 6 10".and a capacity of 15.7 gallons or 130.3 lbs. perinch of heightand mixed with a side entry propeller typev agitator while being heated to 200 F. for l0 minuteswith live steam. The cooked mixture was then diluted W th Water" to 1,000 gallons, or a height of 64 inches from the bottom,'an d maintained at a temperature of. 180 F.

Bond paperwas run oiton'a Fourdrinier machine; The roll width was 106", the-speed 450 corporation, of applicants preferred. mixture. in

the furnish resulted in a mullen increase of approximately 20% in. the bond paper and, when usedinstead of the regular 5%addition of starch at the'fan pump, of approximately 10% in the ledger paper; They also indicatedthat in the ledger run the tearing and folding strengths-were addition of condensate and expansion of the- I Machine Direction...

batch resulted in a total finished volume of; 150 gallons.

Before During After Weight -1 Mullen Points Tear:

Cross Direction Tensile: 1

Machine Direction Gross Direction .QQ.

The tensile strength is expressed in kilograms per 15 mm. width and is a measure of the force parallel to the plane of the specimen required to produce failure under standardized conditions.

The foregoing data indicates that as little as 0.35% of the preferred mixture results in very substantial increases in the bursting, tear and tensile strengths of duplex kraft liner.

EXANEPLE 3 Run No. .1.In a paper mill, five reels of 42 lb. duplex finish liner were run off on a Fourdrinier machine at a rate of 911 feet per minute Run No. 2.More reels of the same paper were run off at 935 feet per minute, or an increase of 24 feet per minute over Run No. 1. mately two hours after this run was begun the mixture added in the first run was again added, this time, however at a rate of 3 lbs. per ton of finished paper at the primary'regulatorbox and. 2 lbs. per ton at the secondary regulator box. The mullen averaged less than before the addition of the locust bean gum mixture and more than 113 after said addition. 7

Run No. Iii-Several more reels were run off on the same machine the next day, the speed being further increased to 942 feet per minute or 19.6 tons per hour. Approximately two and onehalf hours after the beginning of this run, the mixture added in the first and second runs was again added at the primary and secondary regulator boxes at the same rates as in Run No. 2. The mullen averaged 9 8 before, and 111 after the addition of the locust bean gum mixture.

The foregoing data indicates that the method of this invention results in a substantial increase in the bursting strength of paper produced therefrom.

EXAMPLE 4-" l 30 sheets of 8" x 8" paper, each weighing 4.3 grams, were run off ona laboratory scale. Ten were untreated, ten were treated, at the wet end, with-0.5% by weight of locust bean gum alone and ten Were similarly treated with 0.5% by weight of a mixture of 84.9% locust bean gum, 10% borax, 5% glyoxal and 0.1% DowicidefA.

Each of the sheets were testedon a Mullen tester. It was found that the average Mullen counts of the three groups of sheets tested were 34.6, 42.6 and 46.95, respectively, thus indicating that the bursting strength of paper is improved more by incorporating the mixture than by in- I corporating locust bean gum alone.

EXAMPLE v5 Four batches of locust bean g um bQraX glyoxal, corresponding to Formulae. Nos. 1,12, 3

and 4 of Table 1, were made up on a laboratory scale. A 1% aqueous solution ofeach "batchjw as formed by dispersing one part by weight ofthe dry mixture in about 50 parts by weight of water,

cooking the resulting dispersion to 200' and then adding sufiicient additional water tofbring the concentration of solids down to 1% by weight. The temperature of these solutions was main,- tained at about 180 F.

A 1% solution of locust bean gum prepared in a similar manner.

Anumber of paper making runs, on a laboratory scale, corresponding to the number of solutions prepared, were then made. In each run, one of the prepared solutions was added to the furnish at a rate of 10 lbs., based, on the dry weight, of solution to a ton of furnish, likewise based on the dry weight. y Two sheets each having a weight of 2.8 grams were selected from each run to eliminate test errors due to variations inthe weight of the sheets produced and each sheet selected was subjected to ten Mullen tests. Theaverages of the twenty Mullen tests in each run are tabulated below:

alone was 7 Average Formula No. l ullen Count 4.- 32 Locust Bean Gum Alone 30. 85

I EXAMPLE 6 Dry mixtures corresponding to Formulae Nos. 7, 8, 9, 10, 11, 13,14, 16, 18, 19 and 20 were made up, on a laboratory scale into 1% aqueous solu tions by dispersing one part by weight of each dry mixture in about 50 parts by weight in water, cooking the resulting dispersions to 200 F. and then adding sufiicient additional water to bring the concentration of solids down to 1 by weight. The temperature of these solutions wasmain-r tained at about 180 F.

A number of paper making 'runs ona labor a toryscale were then made. In each run, a num ber of blank and modified paper sheets were made. The blank sheets were made withoutadd ing a locust bean gum containing solution to the furnish and the modified sheets were made by adding one of the prepared solutions at a rate of 10 lbs., based on the dry weight, of solution to I a ton of furnish, lkewise based on the dry weight.

Two blank sheets and twomodified sheets ach P n a W h of e e w e eel t e rqa each run to eliminate tsterrors due to variations in the,..weight of the sheets :produced and each sheetf-selected was subjected tosten Mullen tests. The averages ,of the ntwentyatMullen tests con- EXAMPLE 7 In a paper mill, 42.1bs. of a mixture consisting of 85% locust bean gum, 10% borax and glyoxal were slowly added to 200 gallons cold water in a 650 gallon wooden tank and dispersion was obtained without difiiculty. The dispersion was cooked to 200 F. with live steam and held at that temperature for 20 minutes. The steam was turned 01f, the cooked solution was diluted to 500 gallons with cold water to a concentration of 1% by weight of solids and the temperature was maintained at 185-190 F.

84 1b.-135 test kraft liner was run in a cylinder type machine, the solids in the liner furnished consisting of 80% kraft pulp and 20% news pulp and the solids in the filler furnish consisting of 65% old containers and kraft wrappers.

For approximately one hour duringthe run the cooked solution was pumped directly to the headbox at a rate of 5 lbs. of solids per ton of dry furnish and distributed to cylinders by individual valves. u

Mullen tests on the paper produced in this run showed that the mullen of the paper was increased, by the addition of the cooked'solution at the headbox, from anaverage of 1.505 to an average of 1.613, or by 7.2%. u

64 lb.-100 test kraft liner was run on the same machine, the solids in the liner furnish consisting of 80% kraft pulp and 20% news pulp and the solids in the filler furnish consisting of 80% old containers and 20% kraft wrappers.

The results are tabulated below:

Average mullen before and after treatment Average mullen during treatment ncrease.

the appended claims. I

We claim:

1. In a process of making paper from an aqueous suspension of fibrous material, the step which comprises adding, to said suspension, after all operations designed to substantially modify the fibrous constituents by mechanical means are completed and prior to the formation of the web,

an aqueous solution of a cooked mixture of locust bean gum, an alkali metal borate and an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde, the gum being present in said mixture in an amount from at least about equal to the combined weight of borate and aldehyde to about 96% of the mixture, the relative proportions of the bQrate to the aldehyde ranging from about 3:1 to 1:1 by weight, and the amount of cooked mixture of gum, borate and aldehyde in the solution being an appreciable amount up to about 1.5 parts per'100 parts of fibrous materials in the'aqueous suspension, both parts being based on the dry weight thereof.

2.- In a process 5 of making paper from an aqueous suspension of fibrous material, the step which comprises adding, to said suspension, after all operations designed to substantially modify the fibrous constituents by mechanical means are completed and prior to the formation of the web,

an aqueous solution of a cooked mixture containing from 50 to 96parts by'weight of locust bean gum, from 2 to 35 parts by weight of an alkali metal borate and from 1 to 20 parts by weight of an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde, the amount of cooked mixture of gum, borate and aldehyde in the solution being an appreciable amount up to about 1.5 parts per 100 parts of fibrous materials in-the aqueoussuspension, both parts being based on the dry weight thereof.

3. In a process of making paper from an aqueous suspension of fibrous material, the step which comprises adding, to said suspension, after all operations designed to substantially modify the fibrous constituents by mechanical means are completed and prior to the formation of the Web,

' Number .an'aqueous solution of a' cooked mixture containing from to 9 0 parts byweight of locust bean gum, from 5 to 10 parts by weight of an alkali metal borate and from 2 to 6 parts byweight of .an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde, the amount of cooked mixture of gum, borate and aldehyde in the solution being an appreciable amount up to about 1.5 parts per parts of fibrous materials parts being based in the aqueous suspension, both on the dry-Weight thereof.

NAT FRISCH. FRANK J. SWEENEY.

References Cited in'the file of this patent UNITED. STATES PATENTS Name Date (Other references on following page) Irvinget a1. Dec. 18, 1866 

3. IN A PROCESS OF MAKING PAPER FROM AN AQUEOUS SUSPENSION OF FIBROUS MATERIAL, THE STEP WHICH COMPRISES ADDING, TO SAID SUSPENSION, AFTER ALL OPERATIONS DESIGNED TO SUBSTANTIALLY MODIFY THE FIBROUS CONSTITUENTS BY MECHANICAL MEANS ARE COMPLETED AND PRIOR TO THE FORMATION OF THE WEB, AN AQUEOUS SOLUTION OF A COOKED MIXTURE CONTAINING FROM 85 TO 90 PARTS BY WEIGHT OF AN ALKALI GUM, FROM 5 TO 10 PARTS BY WEIGHT OF AN ALKALI METAL BORATE AND FROM 2 TO 6 PARTS BY WEIGHT OF AN ALDEHYDE SELECTED FROM THE GROUP CONSISTING OF GLYOXAL AND PYRUVIC ALDEHYDE, THE AMOUNT OF COOKED MIXTURE OF GUM, BORATE AND ALDEHYDE IN THE SOLUTION BEING AN APPRECIABLE AMOUNT UP TO ABOUT 1.5 PARTS PER 100 PARTS OF FIBROUS MATERIALS IN THE AQUEOUS SUSPENSION, BOTH PARTS BEING BASED ON THE DRY WEIGHT THEREOF. 